Evolution. Hydrogen bonding between the purines, adenine and guanine, and the tripeptide, triglycine, has been demonstrated. Binding in aqueous solution between the peptide Lsy-Ser-Gly-Lys and a newly synthesized 10-member oligonucleotide of cytosine has been shown by measuring the circular dichroism spectrum of (dC)10. Protein Synthesis. The activation of a valyl-tRNA synthetase discovered in this laboratory has been found to be powerfully inhibited by unsaturated fatty acids. These and other lipophilic substances discovered in yeast are implicated in the regulation of growth, possibly through effects on the activation of the first step of protein synthesis -- the aminoacyl-tRNA synthetase reaction.